By memory it's the cams that start to go, somewhere around 400 (on a stock block). As mentioned above, depending on your goals that may be enough to get going. Biggest costs to the swap are likely going to be the custom parts from IMS, which (by all accounts) are well worth the cost/wait.

If there is one thing Jim Green does not have to prove, is the horsepower his cars are making. From all the way back on his 10VT Jim has been making good HP. Once he got into 20VTs, the man has been doing good things. One of the reason we know about the problems with 07Ks, is because of the investigations Jim has done on the motors. One off intercooler and intake manifold, designed to his specs. In the top 5, and that includes shops, in my opinion as far as VEMS tuning goes.

Jim Green does not have to prove anything. If he says his car makes 630whp, then it does.